I've got an old steel patio door with double-pane glass, and one side of the glass has many cracks in it. I'm afraid it's about to fall out at any moment.

We have long-term plans to replace the entire door unit, but we're not there yet, so I'm looking for the cheapest workable solution to having the existing door function as a door (I don't care if the solution leads to fogging between the panes).

I'm thinking about replacing the broken piece of glass with plexiglass. There's a rubber spline on either side of the glass that appears to be holding the glass in.

How likely is it that I can remove that spline, remove the broken pane of glass, insert a piece of plexiglass, and re-insert the spline, while the spacer and second pane stays in place? Or is there a better option?

Here is a photo of actual cracking (the original photo was meant to show the spline). There's a darkening film over the window, or pieces would have already fallen out.

Spline Edge enter image description here

  • Can you accelerate your replacement plan or does that depend on something else first? Also, how old is the door and therefore the other pane of glass? Young glass is a lot more forgiving than old glass.
    – Criggie
    Apr 2 at 1:08
  • 1
    That is/was a real sealed double glazed unit, see the tiny perforations in the spacer/desiccant holder. No way to remove one pane except by awful nibbling until it's a jagged mess.
    – tomnexus
    Apr 3 at 1:00
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    @Criggie It mostly depends on us figuring out what we want. This is one of a pair of sliding doors, and the current opening is much wider than the stairs on the other side of the door, which obviously doesn't make sense. We've been thinking about adding a deck, in which case the double doors would make sense. We also need to feel good that we've actually trained our Doberman not to paw the glass door when she wants out :)
    – Travis
    Apr 3 at 15:55
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    @Travis that sounds like a sub-question for pets.SE but my collie did the same until we added a translucent sticker to the lower glass so he can't see through the window.
    – Criggie
    Apr 3 at 18:39
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    @Travis Maybe try a bell so the dog can tell you she wants out. My Doberman was smart, tall for a female, and so fast. One of the best dogs I've had. And yes...she was a PitA with the door as well. However she caught on quickly to the bell idea, and she would paw at the bell instead. Just a leather strap of jingle bells hung on the door handle or curtain hook will do it.
    – zedmelon
    Apr 4 at 14:48

3 Answers 3


I would overlay acrylic sheet with permanent double-sided foam tape around the edges of the broken pane. This will encapsulate the broken glass for safety and provide some measure of insulation value.

  • What about self-adhesive window film? Could even get a stained-glass pattern for a more interesting look. Or do you believe application would be too difficult over the cracked area?
    – Huesmann
    Apr 2 at 12:22
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    It's not about the application. It's about the utter lack of protection from injury such film provides.
    – isherwood
    Apr 2 at 12:37
  • What's the injury mechanism here?
    – Huesmann
    Apr 3 at 11:38
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    There's a darkening film over the window, or pieces would have already fallen out. I have a hard time trusting tint film of unknown resilience to prevent cuts from contact, especially if kids are involved.
    – isherwood
    Apr 3 at 12:52

In any case, a dual-pane sealed unit (normal for glass doors and most modern windows) does not easily give up the remains of a broken pane - the edges are glued firmly to the spacer separating the two panes.

If you do actually have cracks, or are concerned with the glass falling out in shards, applying a clear stick-on membrane as used for hurricane and vandal resistance would be a better bet than trying to remove a pane from a sealed unit. That will hold all the bits of glass in place, even if it is actually broken.

  • The picture was to show the spline more than the cracks. The cracks are bad enough that some of the glass has pushed past the rest. It's being held together now by darkening tint that had been applied earlier.
    – Travis
    Apr 1 at 18:42
  • This..... did this for a window that was shattered by a pebble ejected by a lawnmower. (using tape)... it held together until the window was replaced.
    – Questor
    Apr 2 at 17:43

I agree with the window film. If replacements not in the budget right now then that would be the best way to keep everything safe until you can get it replaced. They make an opaque window film that is thicker than regular window tint. It's easy to apply you just peel the backing back a few inches to adhere it to the top of the slider and then slowly peel it back as you go down gently pressing it on to the glass. If you peel The backing off all at once you're going to have problems of it sticking to itself or to the glass where you don't want it to. I've used this technique in the past few times on insulated windows as a temporary fix to keep it safe and prevent the glass from breaking more.

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